While demonstrating a high level of skill both as a defenseman and as a forward, Aubrey "Dit" Clapper became one of the league's most versatile performers. In a career that lasted two decades, he forged a reputation as a tenacious yet honest competitor. He rarely looked for trouble on the ice, but if the game turned rough, he was one of the league's more accomplished pugilists. Throughout his pro tenure, Clapper was a respected leader on the ice and in the dressing room. This quality was an asset after he retired and become a coach in the NHL and the American Hockey League.

After a year of seasoning with the Boston Tigers of the CanAm league, Clapper was sold to the parent club in October 1927, and he'd remain in the Bruins' lineup for the next 20 years - becoming the first 20-year man in NHL history. As an experiment, Boston coach Art Ross used Clapper as a right wing, and Clapper adjusted well to his new position. He scored a key goal in the Bruins' first-ever Stanley Cup win in 1928-29, which came at the expense of the New York Rangers in a best-of-three finals.

Eventually Clapper formed the ever-dangerous Dynamite Line with Cooney Weiland and Dutch Gainor. This unit reached its zenith during the 1929-30 season when it led Boston to an unprecedented 38-5-1 regular-season mark. Clapper scored 41 goals in 44 games, second only to Weiland's 43. In 1931 and 1935 Clapper was chosen as the right wing on the NHL Second All-Star Team.

By the 1937-38 season, the Boston defense corps was in need of an overhaul. Meanwhile, the Kraut Line of Milt Schmidt, Woody Dumart and Bobby Bauer had taken on the lion's share of the scoring chores. Clapper was therefore moved back to his original position on defense, and the reassignment inspired him to play some of the best hockey of his career. The work of Clapper and Eddie Shore was crucial to Boston's win over the Toronto Maple Leafs in the 1939 Stanley Cup finals, and between 1939 and 1941 he was named to the NHL First All-Star Team three consecutive times.

Clapper demonstrated his well-known sportsmanship when he scored his 200th career goal at Maple Leaf Gardens on January 8, 1941. After the game, he presented the stick he used to reach this milestone to Maple Leafs assistant general manager Frank Selke as a token of his admiration. Later that year, Clapper contributed five playoff assists as the Bruins won their third Stanley Cup by sweeping Detroit in four straight games.

During the 1941-42 season, Clapper suffered a severed tendon and it was believed that the injury would end his career. Typically, Clapper's resilience and determination inspired him to return the following year with his customary effective play. After the 1943-44 schedule, Clapper was chosen to the NHL Second All-Star Team. In 1945-46, he assumed the role of player-coach and guided the Bruins to a Stanley Cup finals against the eventual champions, the Montreal Canadiens. The following year, unhappy with his diminishing ability, the 41-year-old retired as a player six games into the season.

In an emotional ceremony at the Boston Garden on February 12, 1947, Clapper was honored for his multitude of accomplishments and the Bruins retired his number 5 sweater. In all, Clapper was responsible for 228 goals and 474 points in the regular season as well as 13 playoff goals. He was Boston captain from 1932 to 1938 and again from 1939 until his retirement in 1947. He also served as the Bruins' coach for four seasons and led the team to 78 regular-season wins.

A member of Canada's Sports Hall of Fame, Clapper was elected to the Hockey
Hall of Fame in 1947 when the customary waiting period was waived in recognition of his obvious greatness.